Method and apparatus for heat shrink capping containers

ABSTRACT

A method and apparatus for heat shrink capping an open end of a container is described. Means are provided for simultaneously applying heat to both the top portion of a heat shrink film extending across the open end of the container and an annular marginal edge portion of the film extending over the edges of the container rim against the exterior walls thereof; to thereby simultaneously heat shrink the entire portion of the film which forms the container cap.

United States Patent [191 [111 3, ty [4 Nov. 4, 1975 METHOD AND APPARATUS FOR HEAT 3,427,789 2/1969 Emus 53/42 x SHRINK CAPPING CONTAINERS 3,460,317 8/1969 Carter et 31.... 53/329 3,481,100 12/1069 Bergstrom 53/329 UX [75] Inventor: William T. Doty, Baltimore, Md.

[73] Assignee: Maryland Cup Corporation, Owings Primary Examiner TraviS McGehee Mills, Md. Assistant ExaminerHorace M. Culver A d Filed: Nov. 1974 Attorney, gent, or Fzrm Birch an BlICl'l [21] Appl. No.: 525,876 [57] ABSTRACT A method and apparatus for heat shrink capping an 521 US. Cl. 53/329; 53/42 p 9nd of a container is described MeanS are P 51 Int. cl. B65B 53/06; B65B 7/28 vided for Simultaneously pp y heat to both the top 58 Field of Search 53/30, 184 s, 329, 373, portion of a heat Shrirlk film extending across the p 53/42 end of the container and an annular marginal edge portion of the film extending over the edges of the [56] References Ci d container rim against the exterior walls thereof; to UNITED STATES PATENTS thereby simultaneously heat shrink the entire portion of the film which forms the container cap. 3,120,728 2/1964 Snow, Jr. et a1. 53/42 3,233,386 2/1966 Burke 53/329 SClaims, 4 Drawing Figures l7 l6 l6 Lo I l '1 H a 30A 30 B 1 .1 24 l4 I 1 l US. Patant Nov. 4, 1975 FIG. 2

FIG. 4

FIG. 3

METHOD AND APPARATUS FOR HEAT SHRINK CAPPING CONTAINERS BACKGROUND OF INVENTION 1. Field of Invention The present invention relates to a method and apparatus for capping the open end of a container with heat shrink film.

2. Description of Prior Art Heretofore capping machines and methodsfor apply ing heat shrink film to the open top of a container have employed either a one step process wherein heat is applied only to the marginal edges of a sheet of heat shrink film surrounding theopen end of a container or a two step process wherein heat is first applied to the marginal edges and is then applied in a subsequent step to the portion of the film extending across the top of the container. I

The one step process referred to is similar to the process described in U.S. Pat. No. 3,460,317 to Carter et al, wherein heat is applied only to the marginal edges of the Elm. Processes of this type do not form a seal which is as tight, strong, or leakproof as the seal formed by the method and apparatus of the present invention.

The two step process of the prior art described above suffers from the disadvantage that additional equipment and stations are necessary for performing the second stage of operation, which increases thecost of capping and decreases the speed in which a container can be capped.

SUMMARY OF INVENTION Accordingly, it is an object of the present invention to provide a process and apparatus for heat shrink capping containers which form a tighter seal than known heretofore.

It is a further object of the present invention to provide an apparatus for simultaneously heating both the top portion of a heat shrink film extending across a container opening and marginal edge portions of the film extending over and around the container rim.

It is still another object of the present invention to provide a method for heat shrink capping which is faster and more economical than methods known heretofore.

These and other objects of the present invention are fulfilled by providing a heat shrink capper of the type generally described in U.S. Pat. No. 3,460,317 issued Aug. 12, 1969 to Carter et al and assigned to the same assignee as the present invention. However, in the present invention the tamper or cushion pad had been modified to include radial channels which permit heated air to flow across the top of the heat shrink film on the container simultaneously with the flow of heated air to the marginal edges of the heat shrink film extending around the container rim.

The tamper is further modified to include central openings therein which permit hot air to flow through in a downward direction and pass over the top of the film, thence through said radial channels in the cushion pad.

BRIEF DESCRIPTION OF DRAWINGS The objects of the present invention and the attendant advantages thereof will become more readily apparent with reference to the following description of the drawings wherein:

FIG. 1 is a perspective view illustrating the capping means of the present invention with the component parts thereof in a first position;

FIG.'2 is aside elevational view of the capping means of the present invention illustrating the component parts thereof in a second position;

FIG. 3 is a bottom plan view of the tamper of the present invention; and

FIG. 4 is a side view partially in section illustrating the operation of the capping means of FIGS. 1 and 2.

DETAILED DESCRIPTION OF DRAWINGS Referring in detail to FIGS. 1 to 3 there is illustrated a capping means generally indicated 10 which is suitable for capping a single container at a time. A plurality of units 10 may be provided in juxtaposition to facilitate the simultaneous capping of a plurality of containersf Capping means 10 may comprise a single capping unit to be substituted for unit 68 in a capping machine, such as that disclosed in U.S. Pat. No. 3,460,317 issued to Carter et a] on Aug. 12, 1969. Accordingly, suitable means for operating the component parts of the capping means of the present invention are illustrated in the Carter et al patent and are incorporated herein by reference.

Capping means 10 includes a housing 12 having skirt portion 12A which fits over both the container to be capped and the heat shrink film.

One of the functions of skirt 12A is to shape the heat shrink film which is placed over the container to be capped in a manner which will be more fully described hereinafter.

Housing 12, in a preferred embodiment is cylindrical in shape having the top end closed and the bottom end open for receiving the top of a container 28 to be capped such as shown in FIG. 4. The skirt portion 12A includes a plurality of perforations or inlet holes 14 around the bottom thereof through which heated air is introduced from a source of heated air such as that described in" the above-mentioned Carter et al patent. Skirt 12A further includes a plurality of inlet holes 16 around the top thereof, which extend through an annular seal plate 17. Seal plate 17 is in the form of an annular ring secured within the top portion of housing 12.

For example, the source of heated air may comprise an oven which completely surrounds housing 12 and a blower therein which creates a positive pressure in the oven and forces the heated air through openings 14 and 16 in housing 12. A tamper plate 20 of the present invention is adapted to fit concentrically within housing 12. Tamper 20 is mounted on a stem 18 which passes through an opening in the top of housing 12. Stem 18 is mounted for reciprocal movement by a suitable actuating means in a similar manner to stem 77 of capper unit 68 in the above-mentioned Carter et al Patent.

As shown in FIG. 3, tamper plate 20 is circular in shape and resembles a wheel having a plurality of spokes 22, which define a plurality of central openings 26A, 26B, 26C, 26D therebetween, and a rim or annulus 23.

Mounted on the bottom of tamper plate 20 is an annular cushion pad 24 of resilient material. Pad 24 has a plurality of radial extending channels 24A therein.

DESCRIPTION OF OPERATION The operation of the capper of the present invention is illustrated in FIGS. 2 and 4.

A sheet of heat shrink film 30 is first placed over a container 28 to be capped. Stem 18 is then depressed as shown in FIGS. 2 until cushion pad 24 presses firmly against film sheet 30 and holds it against the top rim of container 28. When capper housing 12 (or multiplicity thereof) is brought down over the top of the container 28, over which has been placed a sheet of heat shrink film 30, cushion pad 24 contacts the top 308 of the film and container and tamper 20 moves up to contact airseal plate 17, as shown in FIG. 4. Hot air from a surrounding oven enclosure (not shown) flows through a first set of ports 16 downward through openings in tamper 26A, B, C 81. D thence across the top of film and out through the radial channels 24A. Simultaneously, hot air from this same oven flows through a second set of ports 14 to contact the marginal edges 30A of film extending around the container rim. In this manner, film is shrunken across the top and under the rim of the container simultaneously.

Accordingly, heat is simultaneously applied both to marginal edges 30A and top portion 308 of heat shrink film 30 to cause bi-axial shrinking to effect a tight leakproof seal about the rim of container 28.

The present invention may be modified as would occur to one of ordinary skill in the art without departing from the spirit and scope of the present invention.

We claim that:

1. In a capping machine for applying a closure to an open top container, said machine comprising a support for the container, means for shaping and disposing a piece of heat shrinkable film on the container to conform to the top thereof in the provision of a top portion of said film extending across said open top and marginal edges of the film adjacent the portion of the wall of the container immediately below the open top, said means comprising an annular skirt adapted to surround the upper end of the container, said skirt having inlet means for the passage of air, a shank slidably mounted for reciprocation within said skirt, a tamper plate secured to the lower end of said shank of a size to fit inside the skirt, means for forcing air through the inlet means in said skirt against said marginal edges, means for heating the air to a temperature sufficient to cause shrinkage of the film, the improvement comprising: flow passage means in said tamper plate in communication with said inlet means in said skirt to permit the flow of heated air across the top portion of said'container simultaneously with the application of said heated air to said marginal edges, whereby said heated air causes both said top portion and marginal edges of said film to simultaneously shrink and forma tight seal between said film and said open top.

2. The apparatus of claim 1 wherein a cushion pad is provided on the bottom of said plate, said cushion pad being in the form of an annular ring and said flow passage means includes a plurality of radial grooves extending through said annular ring from said skirt toward said shank.

3. The apparatus of claim 2 wherein said flow passage means further includes openings in said tamper plate which communicate with said area within said annular ring to permit the flow of air from said area across said top portion of said film and out through said radial grooves in said cushion pad.

'4. The apparatus of claim 2 wherein said inlet means includes a first set of inlet ports spaced around the top of said skirt and a second set of inlet ports spaced around the bottom of said skirt said first set of inlet ports communicating with said openings in said tamper plate means and said second set of inlet ports directly communicating with said marginal edges of said film.

5. The apparatus of claim 4 wherein there is further provided annular seal plate means disposed within said skirt adjacent said 'first set of inlet ports, said annular seal plate means having a plurality of radial passages in communication with said first set of inlet ports, said annular sealplate means forming a seal with the top of said tamper plate when in contact therewith. 

1. In a capping machine for applying a closure to an open top container, said machine comprising a support for the container, means for shaping and disposing a piece of heat shrinkable film on the container to conform to the top thereof in the provision of a top portion of said film extending across said open top and marginal edges of the film adjacent the portion of the wall of the container immediately below the open top, said means comprising an annular skirt adapted to surround the upper end of the container, said skirt having inlet means for the passage of air, a shank slidably mounted for reciprocation within said skirt, a tamper plate secured to the lower end of said shank of a size to fit inside the skirt, means for forcing air through the inlet means in said skirt against said marginal edges, means for heating the air to a temperature sufficient to cause shrinkage of the film, the improvement comprising: flow passage means in said tamper plate in communication with said inlet means in said skirt to permit the flow of heated air across the top portion of said container simultaneously with the application of said heated air to said marginal edges, whereby said heated air causes both said top portion and marginal edges of said film to simultaneously shrink and form a tight seal between said film and said open top.
 2. The apparatus of claim 1 wherein a cushion pad is provided on the bottom of said plate, said cushion pad being in the form of an annular ring and said flow passage means includes a plurality of radial grooves extending through said annular ring from said skirt toward said shank.
 3. The apparatus of claim 2 wherein said flow passage means further includes openings in said tamper plate which communicate with said area within said annular ring to permit the flow of air from said area across said top portion of said film and out through said radial grooves in said cushion pad.
 4. The apparatus of claim 2 wherein said inlet means includes a first set of inlet ports spaced around the top of said skirt and a second set of inlet ports spaced around the bottom of said skirt said first set of inlet ports communicating with said openings in said tamper plate means and said second set of inlet ports directly communicating with said marginal edges of said film.
 5. The apparatus of claim 4 wherein there is further provided annular seal plate means disposed within said skirt adjacent said first set of inlet ports, said annular seal plate means having a plurality of radial passages in communication with said first set of inlet ports, said annular seal plate means forming a seal with the top of said tamper plate when in contact therewith. 